In commercial fishing, spoilage of fish flesh is a constant and major problem. Two major kinds of spoilage are often encountered: 1) The generation of substances in the flesh (bacteria) that are toxic to humans, and 2) The deterioration of the physical color and/or texture of the flesh which, while not toxic, reduces its value in the marketplace. While deteriorization of fish can occur at any point between catching and consumption, a substantial amount takes place immediately after the fish is caught and before it is refrigerated.
For example, bacteria can start to grow if the fish, after being caught, is allowed to remain on deck in a warm or hot atmosphere for a significant period of time before being refrigerated. The second kind of spoilage can occur as a result of fish exertions in thrashing about o deck. In addition, if fish are allowed to thrash about, bruising of the fish itself and of other fish can occur.
In an attempt to avoid these problems, it is common practice to stun fish by a blow to the head as soon as possible after they are brought on deck. Immobile fish are easier to tend to than active fish, thus reducing the time necessary to prepare the fish for refrigeration, and also, obviously, immobile fish do not exert themselves or bruise either themselves or other fish.
Care must be taken not to kill the fish in the stunning operation, since before each fish is chilled its gill-arch should be slit and as much blood as possible drained. If the fish's heart is not pumping, no significant blood can be drained. The business of stunning fish occupies much of a commercial fisherman's time when fishing is "fast and furious", and often the stunning is done carelessly, with the blow either being too light to stun the fish, or so heavy as to kill it. In the former event, a fish may thrash around the deck bruising itself and other fish, and/or reducing the quality of its flesh by its exertions. With large fish, such thrashing can also be dangerous to the fisherman and others on board. In addition, the time on deck of the catch is extended, thereby increasing the opportunity for bacterial contamination. If the fish is inadvertently killed, proper bleeding cannot be accomplished.
Another related problem is the brutalization of fishermen involved in the clubbing of fish and the negative public perception of this practice.
It is therefore an object of the present invention to provide an efficient and economical means for immobilizing caught fish which is easy and fast to apply, and which has little likelihood of either killing the fish or of failing to stun it, even when the fisherman is under great pressure to attend to many fish in a short period of time.